Laminated sheet material



Feb. 6, 1940. L. T. SIBLEY 2,189,409

LAMINATED SHEET MATERIAL Filed Nov. 20, 1937 YINVENTOR ATTORNEY Patented Feb. 6, 1940 I UNITED STATES LAMINATED sneer MATERIAL.

Leon '1'. Sibley, Rutherford, N. 1., assignor to Ali'ol Insulation Company, Inc., a corporation of Delaware Application November 20, 1937, Serial No. 175,547

3 Claims.

My invention relates to laminated sheet materials and more particularly to a double reinforced, heat reflective water-resistant combined sheet material that will satisfactorily resist contraction and expansion caused by natural varying weather conditions, or by artificial varying conditions of humidity. F

Numerous attempts have been made heretofore to produce combined paper sheet material that would be sufficiently waterproof to permit its use as a protective covering for structures or articles exposed directly or indirectly to varying humidity conditions. Also in connection with heat insulating materials various types of laminated paper and felt materials have been tried. As far as I am aware, all of these prior art laminated paper materials possess certain disadvantages that have seriously limited their commer- One of the main defects is that rials, which is used for certain waterproofing and 25 insulating purposes, consists of two heavy sheets of Kraft or similar heavy paper stuck together by means of a layer of asphalt or other adhesive with a matting "of reinforcing fibers, commonly jute or sisal, imbedded in the layer of adhesive 30 between the two sheets. This material has a dark dull surface which is conducive to .heat absorp- I tion instead of heat reflection and its value as a heat insulating material is therefore negligible. It is to some extent water-resistant but does not 35 prevent wetting of its fibrous portions when subjected to water or moisture vapor. These fibers as well as the paper itself on becoming wet tend to stretch and sag thereby causing the material M as a whole to expand considerably in excess of m its original size and area when normally dry; upon drying of the fibers as well as the paper itself the material will tend'to shrink and contract to considerably less than-itsoriginal size f use requires rigidly fastening the material'so that it is not completely free to expand under wet con- 50 ditions and contract under dry conditions.

As a specific example when the above described reinforced laminated paper is fastened by nails,

tacks or the likeover a shipping container as a protection to the container against the weather,

55 as iscommonly done, and is exposed to wet and dry weather or varying atmospheric humidity conditions, the paper will frequently contract to.

' such an extent that it willpull away from the nails thereby breaking the fastening, frequently,

7 conditions. Each area, approximately one-half oo rupturing the paper itself, and rendering .the

cient heat reflective surface or surfaces, and is therefore an efiicient heat insulator. It is highly water-resistant and accordingly'will expand and contract only slightly with varying moisture conditions. Furthermore it is so constructed that this expansion and contraction will not adversely affect any of the combined sheets and will not break the bond between these sheets.

The sheet material of my invention, which is characterized by, the above mentioned desirable features, comprises generally two assemblies of, combined paper sheet and metal foil or other heat reflective material, laminated on opposite sides of anet of fibrous strands which are embedded in a thin layer of asphalt. In developing this finally commercially satisfactory product, which possesses unusual heat insulation moisture vapor and water-resistant properties, I made and tested several other types oflaminate'd sheet materials all of which proved to be unsatisfactory. One of these materials consisted of two sheets of paper bonded together with adhesive and covered .on both sides with sheets of metal foil. Contraction and expansion of the paper sheets under varying moisture conditions caused the metal foil covering to wrinkle and split in numerous places thereby losing its effectiveness as a waterproof covering. Another of the tested materials was like the one -just described except that reinforcing fibrous strands were used between the two combined sheets in one direction. Contraction and expansion of hepaper sheets in this material caused the metal foil covering: to wrinkle and split along the fibrous strands which rendered the material unsatisfactory.

'I finally discovered that by using a fibrous net as the reinforcing center member and by so positioning the paper metal foil assemblies on this v net that a slight excess of paper and foil of each assembly sheet is provided around each of the net strands, themetalfoil covering'would not wrinkle or split and 'no other harmful effects would occur under varying moisture conditions. The apparent secret of success of this construction is that the excess material around each net strand under dry conditions will be used to compensate for the slight expansion that takes placein each of the small confined areas of the sheet under wet inch square is bounded on all sides by the fibrous net strands. The excess material bridges each strand. Expansion or contraction of the sheet is basically limited to each small area because of the fibrous strands that bound and enclose each area. Therefore, movement of the material is confined to each small area which effectively prevents establishing a progressive stress throughout the sheet such as normally occurs in the prior art materials thereby causing rupture of the paper. The excess paper and foil bridged over each strand and the flexible and compressible nature of the strands compensate for slight movements of the material in each area, thereby preventing the paper and foil from rupturing due to those movements. Accordingly, there is insufilcient stress set up between the paper, foil,

and/or fibrous net strands over the entire area of the sheet during contraction or expansion to cause wrinkling or splitting of the foil, or rupture of the sheet.

Regarding the method of assembly of the product of my invention, I found that the metal foil or other heat reflective material could not be applied, with satisfactory results, to paper sheets previously combined and reinforced by the asphalt and fiber net. In other words this product cannot be obtainedby simply covering laminated reinforced paper with metal foil or other heat reflective material, the main d fficulty being that the foil cannot be a plied uniformly and without wrinkling and splitting. The method that I finally determined upon as being commercially satisfactory comprises first combining the paper and heat reflective mater al by means of a suitable adhesive and pressing through rotating rolls and then combinin these assemblies by means of adhesive with the center fiber net. The complete assembly is passed through rotating rolls and is compressed and dried. Passing through these last rolls effectively forms the paper and foil or other heat reflective material assemblies around the fiber net strands. thereby providing along each strand the excess of paper and heat reflectivematerial reouired to com ensate for contraction or expansion under varying moisture conditions.

The novel features of my invention are set forth with articula ity in the ap ended claims. The invention itself however. both as to construction and method of assembly of the sheet material will be easily understood from the following descri tion taken in coniunction with the accompanying drawing, in which:

Fig. l is a plan view, partly broken'away, of one specific form of the material of my invention;

Referring now to the drawing. which it will be understood shows an illustrative but non-limiting example of my invention, the product consists of essentially two outer metallic sheets l and H combined with two inner paper sheets [2 and I3 to form two assemblies, the paper sheets being separated by a reinforcing net of fibers H which extend both horizontally and longitudi- Fig. 2 is a sectional view taken along lines nally. The net I4 is held in place and the paper sheets I! and 13 are held togetherby means of a layer of asphalt or other suitable adhesive shown at l5 applied on the side of each of the paper sheets l2 and I 3 opposite the metallic sheets l0 and II. The metallic sheets l0 and II are secured to the outer surfaces of the paper sheets l2 and I3 by means of any suitable of adhesive indicated at l6. .1

The metallic sheets in and H may be made of any suitable flexible sheet metal such as for example aluminum foil, or any heat reflective material coating either metallic or non-metallic highly heat reflective thereby making the material of my invention particularly suitable for heat insulating purposes. Furthermore, these metallic sheets are substantially waterproof which renders the entire laminated sheet assembly highly resistant to water and the effects of varying moisture conditions. The thickness of these sheets or coatingsv may vary widely. One specific but non-limiting example is a foil of about 0.00035" in thickness. The metal foil sheets l0 and H show practically negligible contraction and expansion with varying weather or atmospheric humidity conditionsyand therefore avoid the numerous difficulties encountered with the prior art types of laminated sheet materials having paper coverings.

The paper sheets l2 and l3,-which according to my invention are covered with metal foil sheets or other heat reflective material may be made of any suitable relatively thin paper. I have found it advanta eous to make these sheets relatively thin com ared with the usual heavy paper and paper board heretofore used in order to reduce substantially the usual tendency of these think sheets to contract and expand appreciably with varyin moisture conditions. I have found that by mak n the sheets l2 and I 3 of relatively thin pa er. for exam le one specific but nonlimitin thickness is 0.003". they will have appreciably less tendency to chan e in dimensions with varying weather conditions. These thin pa er sheets could not be used in the prior art" lam nated pa er materials because of their mechanical weakness and water permeability. In the material of my invention, however, they can be used since they are covered and protected by the water roof metal foil or other heat 're fle ive material sheets Ill and H.

The fiber net cons sting of crossed lon itudinal and horizontal strands I 4 may be composed of any suitable fibrous strands such as for example hem or sisal. Likewise the arran ement of these fibrous strands may vary widely. All of the strands may be uniform arranged or only part of them 'as n icated in Fig. 1.

The usual adhesive for laminating the paper sheets and for holding the reinforcing net in place is asphalt. In the assembly of my invention I have found asphalt to be entirely satisfactory for this purpose, but any other suitable adhesive having sufficient bonding power to hold.

the laminated sheets together may be used. An example of a suitable adhesive for sticking the outer metal sheets l0 and l I to the inner thin paper sheets l2 and I3 is sodium silicate. Other suitabie adhesives for example, ,converted starch adhesives, gutta percha cement, etc., may be used.

The important feature of providing an extill cess oi paper and heat reflective material around each fiber strand it under normally dry conditions is shown in Fig. 2, and the use of this material under wet expanded conditions is shown in Fig. 3. Referring first to Fig. 2, it will be noted that the paper sheets l2 and it with their attached foil sheets it and M extend over and in contact and bridge the top and bottom surfaces of the strands it of the reinforcing net. This is illustrative of the excess amount, i. e. length andwidth, of sheet material when the product of my invention is used under normally dry conditions, conducive to negligible expansion or contraction of the entire sheet. It will be noticed that under this condition the combined paper and foil assembly is more or less in excess of a true fiat area, around and over the strands Mi.

Now, when the product is exposed to water, moisture vapor or other wet conditions normally conducive to expansion and sagging oi the paper sheets the excess bridged material around the strands Ml is used up by its tendency to flatten out and elongate, and the sheet assemblies assume the lengthened condition illustrated in Fig. 3. There is now no appreciable excess of material formed around the strands t l. It will also be noted in this figure that the strands i l have been compressed slightly from their normal round form shown in Fig.2 to a more or less elliptical form. This also helps to prevent rupture of the sheet material upon expansion.

In Fig. 4 there is illustrated the material after being wet and dried. It will be noted that the contraction of the sheet results in humps of the foil and paper around the net strands even in excess to that present under normally dry con ditions shown in Fig. 2.

While I have expressed above my understanding or theory of how the product of my invention reacts under varying moisture conditions to give satisfactory use, I wish it to be understood that my invention should not be limited to this or any other theory. Whatever the correct explanation is, the important fact is that the product does give satisfactory results under wet and dry weather conditions and thereby constitutes a substantial improvement over the materials tested and tried heretofore.

One of the commercial uses for which my product has proven particularly adaptable is in the insulation oi railroad cars. In these cars and especially refrigerator cars the insulating material which lines the inner walls is subjected to vng degrees of moisture and unless the material'is capable of withstanding these changes it will tear or disintegrate and lose its efiective ness m an insulator. The laminated sheet material of my invention is substantially waterproof and 11 therefore withstand subjection to these wet refrigeration conditions. Its light metallic or other heat reflective smiace provides eficient heat reflection and therefore resists the transfer oi heat through the railroad car walls. her

more, it is of suficient stability and rigidity to permit its use without supporting frames or panels. It may be installed by simple attachment to cross members at top and bottom, there by sag material and labor. It uses no felt or other t of mass it a ation material and there tore avoi the detects oiwater ht this purpose the sheet material is placed directly behind the laths and plaster and will prevent the infiltration of moisture laden air into the wall or roof structure of the building, whereby insulation against heat and moisture is obtained. From the foregoing description it will be understood that the material of my invention comprises principally a plurality of flexible heat reflective waterproof metallic sheets or non-metallic coating joined together in superimposed relationship through the intermediary of a plurality of relatively thin paper sheets adhesively fastened together and reinforced by a matting oi fibrous strands.

As suggested hereinabove, it will be understood that my invention is not limited to the specific embodiments shown and described, but is subject to various modifications and changes as to size and type of materials and their method and arrangement of formation, including a laminated product of generally similar construction to the product shown except for use of the heat refiective sheet or coating on only one side of the material.

I claim:

1. A foil covered, reinforced, laminated sheet material which will permit limited relative move= ment under varying moisture and temperature conditions without splitting or otherwise adversely affecting the foil comprising two sheets of relatively thin paper, an intermediate net of reinforcing vegetable fiber strands having a thickness substantially greater than that of the paper sheets, said net being interposed between said paper sheets and bonded thereto by a layer of adhesive which also holds said sheets together, a relatively thin metallic foil covering the outer surface of at least one of said paper sheets, said paper sheets and foil covering being firmly pressed against said fiber net so that the crossing strands of the not form a network of crossing ridges in the paper and foil sheets, which correspond in number and distribution to the fibrous strands of the net and subdivide said sheets into a plurality of small areas bounded on all sides by said ridges, said ridges serving to confine within each respective small area the contraction and expansion of the material in said area which effectively prevents a progressive stress being 3. A foil covered, reinforced laminated sheet material as defined in claim 1 in which each oi. the paper sheets has a thickness not substan= tially greater than about 0.003 inch and the toll is substantially is: than the paper sheets.

" LEON T. 

